The present invention relates to forming films during semiconductor device/integrated circuit fabrication and more particularly to depositing silicon nitride films during fabrication.
Semiconductor devices may include several layers deposited or grown on a semiconductor substrate. For example, dielectric layers may be formed to separate metal layers. Two dielectrics widely used in semiconductor device and integrated circuit design include silicon dioxide and silicon nitride.
Silicon nitride may be preferred to silicon dioxide in certain applications. For example, a silicon nitride film may be preferred as a final passivation layer to protect against device contamination. Further, silicon nitride may be preferred material for barrier layers and etch stops.
To create local areas of oxidation on silicon for isolation purposes, a silicon nitride layer may be deposited on a silicon substrate. The silicon nitride layer may be patterned to create islands of silicon nitride separated by silicon. Thereafter, exposed silicon is oxidized. In contrast, silicon beneath the silicon nitride is not oxidized. After patterned oxidation, the remaining silicon nitride may be removed. As such, regions of the substrate surface are separated by isolating regions of oxide. In sum, silicon nitride films may be used in a variety of applications including front and back end processing.
Historically, the use of silicon nitride films was limited due to the high temperatures needed for deposition using conventional techniques and deposition precursors. In fact, deposition of silicon nitride at temperatures above 660° C. may cause damage to devices or components including alloying of aluminum.
Thus, there continues to be a need to improve silicon nitride deposition techniques especially silicon nitride deposition at low temperatures.